A comparison study on growth, reproductive and food habit of Mesopotamichthys sharpeyi in the Al-Diwaniya River, middle of Iraq

Abstract

Biological aspects of Mesopotamichthys sharpeyi was studied in terms of length and weight, age, growth, sex ratio, size at first sexual maturity, gonad development (GSI) and food habit in the Al-Diwaniya River, Iraq. These biological features were compared with other studies on the species. Fish were collected by different fishing gears. The length–weight relationship was calculated for fish sizes 11 to 39 cm as W = 0.032L 2.7017, with negative allometric growth. The monthly fluctuation in the relative condition factor of the species was influenced by the spawning cycle and feeding intensity of the fish. Seven ages were identified from scales and the mean lengths of these ages were 11.8, 21.4, 26.2, 30.5, 34.5, 37.8 and 41.1 cm, respectively. von Bertalanffy growth parameters were L∞= 56.0 cm, K= 0.229 and t0= - 0.103 years. The growth performance index (Φ) was found to be 1.99. The overall male to female ratio (1:1.48) was biased in favour of females. Length at maturity was 33 cm for males and 34 cm for females. The GSI was at the highest level in April then dropped dramatically for both sex, suggest that the species may spawn in late April to May. M. sharpeyi is a herbivore fed on macrophytes, algae, detritus, and diatoms. Some biological properties of the species were among those described for the species in other waters.